Large (2-watt and up concentrated arc lamps find widespread application in scientific fields and elsewhere including use as light sources for Schlieren, shadowgraph and other flow visualization techniques. A serious drawback in the operation of such lamps is the intermittent or otherwise unreliable performance of the associated power supplies. Such lamps make very substantial demands on their power supplies in that a starting voltage of in excess of 1000 volts is required whereas, when the arc is stabilized, the voltage drop across the lamp is approximately 20 volts. Conventional operating techniques involve supplying the lamp from a constant voltage in excess of 50 volts, with a series resistance being used to limit the current to about 1.25 amperes. This series resistance also serves to eliminate the effect of the negative resistance of the lamp arc. The starting voltage for the lamp is conventionally provided by a relay-choke combination which produces a high voltage spike by inductive kickback. This technique for generation of the starting voltage is the weakest feature of such conventional power supplies.
There are, of course, many different designs for power supplies for many different applications. Patents of interest in this general field include U.S. Pat. Nos. 3,544,840 (Saiger); 3,629,647 (Lake); 3,665,247 (Gordon); and 3,849,717 (Walz et al). The Walz et al patent discloses a circuit for gas discharge lamps wherein both supply and firing voltages are provided by a voltage multiplier comprising a plurality of voltage doubler circuits. The Saiger patent discloses a supply circuit for a gas discharge lamp such as a xenon tube which employs a transformerless multiplier of the capacitor-rectifier type in combination with a pulse trigger circuit. The Lake patent discloses a voltage doubling starting circuit for a gas discharge lamp comprising a pair of diodes and a pair of capacitors connected in a voltage doubling configuration in combination with a bleeder resistor. The Gordon patent discloses a power regulating circuit for light amplifier tubes which includes a voltage multiplier formed by capacitors and diodes.
Other patents of more general interest include U.S. Pat. Nos. 3,911,191 (Patrick et l); 4,241,360 (Hambor et al); and 4,389,703 (Morel et al). These patents relate to voltage multiplier circuits employing capacitors and diodes, with the Petrick et al patent being concerned with a Cockcroft-Walton cascade circuit.